Feedback systems for elevators are used to track the position or speed of an elevator cab as it is moved along an elevator hoistway. More specifically, elevators employ encoders that are configured to monitor the rotational displacement and/or speed of a traction motor that may be driving the elevator cab through the hoistway. Using known mechanical relationships between the traction motor, traction sheaves, tension members and the hoistway, the data provided by the encoder can then be used to determine the position and/or speed of the elevator cab with respect to the hoistway.
Although encoders may prove to be an adequate solution for monitoring elevator control, the costs of encoders and implementations thereof have led to increased efforts in developing comparable encoderless solutions for providing efficient feedback of elevator control. However, existing encoderless implementations can be excessively complex in design and impractical. Existing encoderless applications can also have noise, reliability and inefficiency (especially at low elevator cab speeds) issues.
Accordingly, there is a need for systems and methods which provide encoderless and cost-effective means for controlling an elevator with suitable reliability and performance. Moreover, there is a need for relatively quiet systems and methods capable of providing consistent feedback for elevator controls throughout the entire range of operational speeds of an elevator.